Norway Rat

Color

Brown with scattered black hairs, gray to yellowish-white on underside.

Characteristics

The name is a misnomer; the Norway rat is not Norwegian at all. The name is supposed to come from where it was classified. But what's in a name anyway; other aliases include brown rat, sewer rat, barn rat, water rat, grey rat, and wharf rat. They could do with shedding a few pounds, and their fur is coarse and shaggy. They have small ears and eyes, and a scaly two-colored tail.

Droppings

With a bigger rat comes bigger...well you know. Up to ¾ inch (20 mm) long, and capsule-shaped.

Where Found

Previously in Central Asia, north of the Caspian Sea, but now found pretty much everywhere.

Habitat

Norway rats are well-prepared for emergency. They dig burrows with hidden emergency exits. Any place will do; railroad embankments, piles of garbage, under concrete. Naturally adapted to flat, dry, grassy plains.

Food

Norway rats are big foodies. Though that doesn't necessarily mean they all have sophisticated palates on par with Ratatouille. Not to say they'll eat anything, but they do like lots of meat, fish and dry dog food. They admit they have an addiction to buffets, and tend to gorge themselves, then come back for more later. These rats will gnaw through anything to get to their food, even plastic or lead pipes.

Biology

All that eating comes with a lot of social time. Might as well start a neighborhood so they can have potlucks and block parties. Pregnancy takes 3 weeks, with 3-6 litters per year and 7-8 young a litter. Newborns grow hair after 1 week, open eyes in 2 weeks, are weaned at 3-4 weeks, and mature in 2-5 months. Adult life lasts 6-12 months or longer, if in captivity. Other than their vision, their senses are keen (touch with long whiskers). They are color-blind. They are nocturnal, and can run, climb, jump, swim, and love to explore.

Damage

What don't they do? They gnaw on objects, eat stored food, and transmit disease by droppings, urine, bites, fleas and mites in their fur.

Invasion

Openings must be larger than ½ inch to squeeze through.

Good Riddance

Overall, the key to controlling rodents includes sanitation, elimination of their shelter, and rodent-proofing the structure. With Norway rats, look for evidence of burrows. Gnaw marks, droppings, footprints, and 'tail-drag' marks are signs they've already infiltrated your home, as well as dark greasy markings that come from rubbing against things.

Cleaning up spillage will enhance the chances of rodents visiting control measures. Getting rid of rodent evidence allows monitoring of the population control, while removing clutter and excess storage allows the setting of control measures and monitoring for population decrease. Exclusion is an important aspect of rodent control in structures. Most rodent problems are a result of indigenous species seeking food and shelter in our homes or businesses. Rodents also have an advantage; they can "flatten" their bodies to fit through openings (¼ inch for mice). A thorough inspection is important to identify entry points and to repair them, and is the only way to achieve long-term control in areas where this rodent is indigenous. Once the entry points have been repaired, use of mechanical trapping devices is recommended. We do not recommend the use of rodenticides inside residential properties. When using any rodenticide, read the entire label prior to use. Follow all label instructions, restrictions and precautions.